Motor vehicle heat exchanger system

ABSTRACT

A motor vehicle heat exchanger system with a closed circuit for an operating medium is disclosed, which includes an evaporator for evaporating the operating medium and a condenser for condensing the vaporous operating medium. Between the condenser and the evaporator a compensation container for receiving the operating medium is integrated. The compensation container is arranged in the cooling fluid stream and can be cooled by the cooling fluid stream.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of German Patent Application, Serial No. 10 2015 107 473.7, filed May 12, 2015, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates to a The invention relates to a motor vehicle heat exchanger system.

The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.

The use of lost thermal energy in the exhaust gas of the internal combustion engines of motor vehicles offers several possibilities to increase the efficiency of motor vehicles. In this connection the use of waste heat for heating the passenger compartment offers the possibility to dispense with additional heating measures thereby reducing fuel consumption. In addition the waste heat can be used for shortening the warm-up phase of drive components of a motor vehicle. Hereby mechanical power loss and with this motor load and motor consumption during the warm-up phase can be reduced.

The recovery of waste heat generated during combustion processes of the motor thus offers a great potential for saving fuel and can contribute to increasing the comfort of driving or using a motor vehicle.

EP 0 832 411 B1 or DE 696 06 296 T2 disclose a method for transporting liquids in a micro-fluid circuit system with a capillary pump for transporting heat. In the circuit at least one evaporator and a condenser and a container for receiving a heat transmitting fluid or operating medium is provided. The evaporator has an outlet, which is connected with the inlet of the condenser via an evaporator line. An outlet of the condenser is connected with the compensation container. The evaporator contains an evaporator body with a permeable material in order to evaporate the operating medium by heat absorption and to generate a capillary pump pressure in the circuit. The reservoir and the evaporator are thermally isolated against each other and are connected with each other by a line. Hereby the container is constructed so as to kept at a lower temperature than the evaporator. This is intended to enable a heat exchange with a minimal temperature difference between the heat source and the condenser.

The state of the art also includes a heat transport device that relies on a capillary pumping action as disclosed in the reference WO 2013/037784 A1 by using a two-phase operating medium. This heat exchanger system includes an evaporator with a micro-porous body, a condenser and a compensation container with an inlet and an outlet. The compensation container has multiple regions that are separated from each other but are in fluid communication with each other. This is intended to avoid disadvantageous influences that occur during mixing of the operating medium and may lead to a pressure decrease.

A similar heat transport device is disclosed in WO 2013/037785 A1, wherein between the compensation container and the micro-porous body of the evaporator a check valve is provided, in order to prevent a backflow of the operating medium from the evaporator into the compensation container. This is intended to prevent the evaporator from drying out.

It would therefore be advantageous and desirable to provide a motor vehicle heat exchanger system which is improved regarding the required mounting space and its use and to increase its efficiency.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a motor vehicle heat exchanger system with a closed circuit for circulating an operating medium, said heat exchanger system including an evaporator for evaporating the operating medium; a condenser for condensing the operating medium from a vaporous state, wherein the condenser is integrated in a cooling fluid stream; and a compensation container for receiving the operating medium, wherein the compensation container is provided between the condenser and the evaporator, and is coolable by the cooling fluid stream.

In the condenser of the motor vehicle heat exchanger system the vaporous operating medium originating from the evaporator is condensed. For this the condenser is integrated in a cooling fluid stream and is impinged with cooling fluid, wherein the cooling fluid flows against the condenser or flows around or through the condenser. The cooling fluid can be a gas, in particular air, or a liquid for example oil.

The motor vehicle heat exchanger system according to the invention is advantageous regarding mounting space and in terms of application. The integration of the compensation container in the zone of influence of the cooling fluid makes it possible to maintain a low pressure level in the circuit. This leads to an increased efficiency and is advantageous regarding application. As a result of the integration o of the compensation container in the zone of influence of the cooling fluid stream the available mounting space in the motor vehicle can also be used effectively. The same applies to complex valve arrangements and check valves.

The motor vehicle heat exchanger system according to the invention is characterized in particular by a high heat transfer density which increases the efficiency of the motor vehicle heat exchanger system.

According to another advantageous feature of the invention, the compensation container can be cooled by the cooling fluid stream. This results in an additional heat source. This additional heat source can be used for heating purposes in the motor vehicle for example for heating the interior or for heating drive components such as the transmission or the motor oil.

A further important advantage of the motor vehicle heat exchanger system according to the invention is the high spontaneity, i.e., the response characteristics and in particular that the transport of the operating medium in the circuit is ensured by the heat input itself. This means that no other auxiliary users such as a pump are required. This increases the efficiency of the motor vehicle heat exchanger system and lowers the costs of the system.

The compensation container in the motor vehicle heat exchanger system according to the invention has essentially two functions, i.e., generation a reserve of operating medium and on the other hand receiving the portion of the operating medium that was displaced by the vapor and to maintain the pressure in the system on a lowest possible level.

An important aspect of the invention is that the cooling of the compensation container and the condenser are combined. As a result the cooling air stream for cooling the compensation container and the condenser is used and the obtained heat is used in the motor vehicle for heating purposes, for example with the air stream for the heating the interior compartment.

According to another advantageous feature of the invention, the compensation container can be arranged in the cooling fluid stream upstream of the condenser.

According to another advantageous feature of the invention, the compensation container can be arranged in the cooling fluid stream downstream of the condenser.

An aspect which has proven advantageous in praxis is that the compensation container is integrated in the condenser. In particular the condenser and the compensation container form a constructive unit. It is also advantageous when the compensation container is arranged below the condenser. In particular the compensation container is arranged directly below the condenser and is directly connected to the condenser outlet of the condenser.

Geometrically the compensation container is adjusted to the particular application at hand and the arrangement in the cooling air stream. Hereby a compensation container, for example a round or square compensation container, can be arranged below the actual condenser. Further a tubular compensation container can be integrated in the cooling air stream. In addition it is possible to integrated the compensation container in the cooling fluid stream so that the compensation container is apart of the cooling fluid channel though which the cooling fluid is conducted. Hereby the compensation container can for example be integrated in the sidewall of the cooling fluid channel in the manner of a water pocket.

The efficiency of the motor vehicle heat exchanger system according to the invention can further be increased by providing for a pressure compensation between the evaporator and the compensation container. For this purpose means for the pressure compensation between the evaporator and the compensation container are provided. In particular the evaporator and the compensation container are connected with each other via a pressure compensation line. This ensures a low pressure level in the circuit. As a result of the pressure compensation between the evaporator and the compensation container, the operating direction of the circuit can be influenced in particular regarding startup behavior. This also enables stabilizing the temperature in the startup phase, which is advantageous regarding efficiency or performance of the system. In particular a high temperature difference between the vapor line and the condenser line is archived, which is advantageous for the system.

The evaporator is in heat conducting contact with a heat source of the motor vehicle. Particular advantageously the evaporator is integrated in the exhaust gas stream of the internal combustion engine of the motor vehicle. This makes it possible to use the waste heat of the hot exhaust gas.

According to another advantageous feature of the invention, the evaporator of the motor vehicle heat exchanger system includes multiple evaporator modules. The evaporator modules are preferably combined with each other so that a passage is formed between them for the hot exhaust gas stream that originates from the internal combustion engine.

In this connection it is also advantageous that the evaporator or one or each evaporator module has a housing and a capillary structure arranged in the housing. The housing is preferably made of a material with good heat conducting properties in particular a metal, preferably steel, in particular a stainless steel. It is also possible to use a housing made of copper or aluminum. The housing can also be made of ceramic materials. The capillary structure in the interior of the housing is in particular formed by a porous plate body made of a sintered material. In particular the capillary structure is metal based.

A motor vehicle heat exchanger system with an evaporator or evaporator module and integrated capillary structure is particularly advantageous within the framework of the invention. The compensation container has the function to generate a reserve of operating medium so that the capillary structure is fully saturated under all operating conditions. Moreover, the compensation container ensures that the portion of the operating medium that was displaced by vapor from the capillary structure is received and the pressure in the system is kept to a lowest possible level.

The motor vehicle heat exchanger system according to the invention renders the recovery of waste heat generated in the combustion process more efficient and with this contributes to saving fuel or reducing fuel consumption.

As mentioned above, in the motor vehicle heat exchanger system an additional heat source is created by the cooling of the compensation container. This available additional heat source can be used for heating purposes in the motor vehicle for example for heating the interior of the motor vehicle.

Advantageous in praxis is the integration of the compensation container into the cooling fluid stream, in particular the cooling fluid stream of the air conditioning module of a motor vehicle. This creates a usable heat sink for the cooling of the compensation container and at the same time the dissipated heat can additionally be used in the motor vehicle for heating purposes, for example heating of the interior of the motor vehicle.

In particular the motor vehicle heat exchanger system is characterized by the stable start-up behavior in the circuit. A particular advantage results from maintaining a low pressure level of the vapor circuit or the circuit of the operating medium in the startup phase. In the system a significantly low pressure level is present at efficient performance.

The motor vehicle heat exchanger system particularly efficiently uses the waste heat originating from the exhaust gas. The exhaust gas temperature is reduced by the heat withdrawal via the evaporator.

The compact construction of the system or of components of the system, in particular the combination of the compensation container with the condenser further results in advantages regarding mounting space and enables saving additional system components such as valves and potentially complex gaskets.

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

FIG. 1 shows a technically simplified illustration of a first embodiment of a motor vehicle heat exchanger system according to the invention,

FIG. 2 shows a second embodiment of a motor vehicle heat exchanger system with the schematic representation of the circuit for the operating medium and

FIG. 3 shows a third embodiment of a motor vehicle heat exchanger system with a schematic representation of the circuit for the operating medium

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Throughout all the Figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

FIGS. 1 to 3 show respectively technically simplified illustrations of a motor vehicle heat exchanger system A, B, C.

Each motor vehicle heat exchanger system A, B, C has a closed circuit for an operating medium OM and includes an evaporator 1 for evaporating the operating medium and condenser 2 for condensing the vaporous operating medium OM. Between the condenser 2 and the evaporator 1 a compensation container 3 is provided. The evaporator 1 is integrated in the exhaust gas stream EG of an internal combustion engine of a motor vehicle. The condenser 2 is integrated in a cooling fluid stream CS. The cooling fluid CF can be a gas, in particular air, or a liquid, for example oil. The condenser 2 is impinged in the cooling fluid stream CS with cooling fluid CF wherein hereby cooling flood CF flows against or around or through the condenser 2. The cooling fluid stream CS is herby indicated by a schematically shown channel 4.

The evaporator 1 includes preferably multiple evaporator modules 5, 6. The evaporator modules 5, 6 are configured cassette-like with a housing 7 made of a housing shell and a cover. In the housing 7 of each of the evaporator modules 5, 6 a capillary structure 8 is arranged. The capillary structure 8 is formed by a porous plate body made of a sintered material, in particular on metal basis. The evaporator 1 or the evaporator modules 5, 6 are in direct contact with the hot exhaust gas EG originating from the internal combustion engine. In an advantageous embodiment the evaporator modules 5, 6 are connected so that the exhaust gas EG is conducted through the evaporator 1 through a passage (not shown) formed between the evaporator modules 5, 6.

As a result of the heat on the exhaust gas stream EG the operating medium OM is evaporated in the evaporator 1. The vaporous operating medium OM is received in a vapor collection chamber 9 of the evaporator 1 and form there conducted via a vapor line 10 into the condenser 2. In the condenser 2 a heat exchange with the cooling fluid CF takes place. This causes the operating medium OM to be cooled and to condense. From the condenser 2 the operating medium OM reaches the compensation container 3 and from the compensation container 3 is conducted via a condensate line 11 to the inlet 12 of the evaporator 1.

The compensation container 3 is integrated in the motor vehicle heat exchanger system A, B, C in the cooling fluid stream CS and can be impinged with cooling fluid CF. As a result the compensation container 3 is cooled by the cooling fluid stream CS. The system pressure essentially depends on the temperature of the operating medium OM in the compensation container 3. As a result of the cooling of the compensation container 3 in the cooling fluid stream CS the pressure level in the circuit can be kept low. Moreover, the cooling of the operating medium OM in the compensation container 3 also enables stabilizing the temperature in the circuit and with this a control of the direction of flow of the operating medium OM in the circuit. As a result of the temperature difference between the condensate line 11 or at the inlet of the evaporator 1 and the outlet 13 of the evaporator 1 and the vapor line 10, the operating medium. OM flows in the circuit without requiring an additional externally driven circulating device, for example a pump. The direction of flow of the operating medium OM is indicated by the arrowheads on the condensate line 11 and the vapor line 10.

In the motor vehicle heat exchanger system A, as shown in FIG. 1, the compensation container 3 is arranged directly downstream of the condenser 2 and in particular integrated in a common housing 14 together with the condenser 2. The condenser 2 and the compensation container 3 form a constructive unit in which the compensation container 3 is arranged below the condenser 2. Between the evaporator 1 and the compensation container 3 a means 15 for pressure compensation is provided. The means 15 for pressure compensation include a pressure compensation line 16, which connects the compensation container 3 and the evaporator. Via the pressure compensation line 16 a pressure compensation takes place between the evaporator 1 and the compensation container 3. This allows vapor bubbles, which form in the region of the inlet 12 on the liquid side of the evaporator 1 to escape.

In the motor vehicle heat exchanger system B, as shown in FIG. 2, the compensation container 3 is arranged in the cooling fluid stream CS downstream of the condenser 2 and the cooling fluid stream CS flows against or around the condenser 2. Also in this case the compensation container 3 and the evaporator 1 are connected by a means 15 for pressure compensation in the form of a pressure compensation line 16.

The motor vehicle heat exchanger system C shown in FIG. 3 is generally constructed similarly. In the motor vehicle heat exchanger system C the compensation container 3 is arranged in the cooling fluid stream CS upstream of the condenser 2 and cooling fluid CF directly flows against the compensation container 3 before the cooling fluid CF comes into heat exchanging contact with the condenser 2. A pressure compensation between the compensation container 3 and the evaporator 1 is again accomplished via means 15 for pressure compensation in the form of a pressure compensation line 16. 

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: What is claimed is: A motor vehicle heat exchanger system with a closed circuit for circulating an operating medium, said heat exchanger system comprising: an evaporator for evaporating the operating medium; a condenser for condensing the operating medium from a vaporous state, said condenser being integrated in a cooling fluid stream; and a compensation container for receiving the operating medium, said compensation container provided between the condenser and the evaporator, and being coolable by the cooling fluid stream.
 2. The motor vehicle heat exchanger system of claim 1, wherein the compensation container is arranged in the cooling fluid stream upstream of the condenser.
 3. The motor vehicle heat exchanger system of claim 1, wherein the compensation container is arranged in the cooling fluid stream downstream of the condenser.
 4. The motor vehicle heat exchanger system of claim 1, wherein the compensation container is integrated in the condenser.
 5. The motor vehicle heat exchanger system of claim 1, wherein the condenser and the compensation container together form a structural unit.
 6. The motor vehicle heat exchanger system of claim 1, wherein the compensation container is arranged below the condenser.
 7. The motor vehicle heat exchanger system of claim 1, wherein the evaporator includes multiple evaporator modules.
 8. The motor vehicle heat exchanger system of claim 1, further comprising means for a pressure compensation between the evaporator and the compensation container. The motor vehicle heat exchanger system of claim 7, wherein the evaporator or the evaporator modules have a housing and a capillary structure arranged in the housing.
 10. The motor vehicle heat exchanger system of claim 9, wherein the capillary structure is formed by a porous plate body made of a sintered material.
 11. The motor vehicle heat exchanger system of claim 1, wherein the evaporator is integrated in the exhaust gas stream of the internal combustion engine. 